There are a wide variety of containers used for shipping products over conventional channels. Whether shipping is done by air, cargo vessel, rail or truck, all shipping containers must exhibit certain basic characteristics depending upon the product being transported. The present invention deals specifically with containers which are useful in shipping products which are perishable or otherwise require maintaining a somewhat consistent temperature independent of ambient conditions. Most often, containers include cold packs or, in some instances, hot packs and insulative side walls which help to maintain stable temperatures throughout the shipping process. The use of a vacuum to minimize heat transfer is well known. For decades, vacuum bottles have been used having an internal volume and evacuated side walls to reduce thermal transfer.
More recently, it has been discussed in the literature that heat transfer can be reduced if the internal volume of a shipping container, as opposed to its side walls, is subjected to vacuum.
Specifically, U.S. Pat. No. 5,918,478 is directed to an insulated chest for storage of items at elevated or reduced temperature which has enhanced insulation, and a cover sealed tight by use of vacuum. The separate cover, four sidewalls, and bottom are formed with dual wall construction (relatively heavy plastic with insulation in-between). When the chest is manufactured, the sidewalls and bottom are internally evacuated and sealed to enhance their insulative qualities. After items are placed in the container with charged heating or cooling elements as needed, the hinged cover is closed and a vacuum pump is attached to a valve conduit that passes through the cover so as to draw a vacuum in the container. The vacuum seals the cover onto the chest and enhances the thermal security of the contents. A wrench is inserted into a channel in the cover to turn a valve to a closed positioned so the vacuum pump may be removed with the vacuum maintained in the chest for storage and transportation.
U.S. Publication No. 2007/0264485 is directed to several embodiments of enclosures using aerogel insulative blankets for holding a host of different materials. The volume and shape of the enclosure may be determined based on the aerogel material or the internal surface of non-aerogel material. The aerogel material may be an organic, inorganic, or a hybrid of organic/inorganic materials. In one embodiment, insulated strips and labels suitable for insulating beverage containers may be formed, with the insulative quality augmented through the use of vacuum during manufacture of the labels. According to the publication, a rough vacuum in a sealed label of approximately 100 TORR would result in a decrease in thermal conductivity by nearly a factor of 2.
U.S. Pat. No. 5,325,281 is directed to an insulated shipping container that uses vacuum insulated panels and expanded polystyrene panels. The container illustrated as a rectangular parallelepiped, is itself formed of four containers that fit snuggly within one another and are easily removed from the assembly to be replaced if damaged. The outer closeable container is formed of corrugated cardboard. Inside this outer container is the first insulating housing that is formed of expanded polystyrene. Within the polystyrene housing is the second insulating housing formed of vacuum insulated panels. Inside this vacuum insulated panel housing is an inner closed container of corrugated cardboard.
U.S. Publication No. 2007/0095712 is directed to a shipping container for transporting biologically hazardous materials safely, even at high altitudes. The outer box of the container is intended to be rigid and gas permeable (constructed for example from corrugated cardboard). The outer box includes an inner box constructed of expanded polystyrene foam insulation such as Styrofoam. The interior enclosure is a flexible bag preferably made of polyethylene plastic that is sized so as to be capable of engaging the interior of the exterior enclosure. When biologically hazardous materials are placed within the interior of the bag, the bag is then at least partially evacuated. The bag preferably includes lines providing visual indications to guide its evacuation and seal.
U.S. Publication No. 2007/0157564 is directed to a vacuum package system for transporting a plurality of medical containers. The packaging system 10 includes a tray 14 that holds a plurality of medical containers 16, such as vials. When the containers are disposed in the tray and prepared for shipment, the tray is inserted into an air impervious vacuum bag. A vacuum is applied to the vacuum bag. When fully evacuated, the bag is sealed to embrace the vials and holds them from moving.
There are certain limitations inherent in the use of prior shipping containers which have been recognized and addressed in the present disclosure.
Recognizing that many products sold in this country are manufactured off shore, shipping volumes become of paramount economic interest. Manufacturers in, for example, Asia, attempt to house as many packages as possible within containers loaded on containerized vessels for transoceanic shipment. Sophisticated shipping containers such as those contemplated herein and in the prior art are provided with valves and insulated walls which occupy shipping volumes which, if reduced, could greatly improve the economies of containerized shipment. As such, it is one object of the present invention to provide a container which can be reduced in volume to the extent practical for maintaining the integrity of the product residing within its internal volume.
Yet another issue unaddressed by the prior art involves dealing with changes in internal pressure which inherently occur over time. For example, if dry ice was used as a coolant, the dry ice would sublimate and increase the pressure of the container. Under certain circumstances, a change in pressure could be dealt with by installing a valve through the side wall of the container but, in some instances, that is not a practical solution. Thus, it is yet another object of the present invention to provide a shipping container which can deal effectively with changes in container pressure whether or not a valve is employed.